Signal-receiving system



B. BRADBURY.

SIGNAL RECEIVING SYSTEM.

APPLICATION FILED MAR.23. 1921.

Inventor: Burke Bradbu r1 His Att orneg Patented Unit. 3, 1922.

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BURKE BRADBURY, 0F SCHENECTADY, NEW YORK. ASSIGNQR T0 GENERAL ELECTRIC! COMPANY, A CORPORATION OF NEW YORK.

SIGNAL-RECEIVING SYSTEM.

Application filed March 23, 1921. Serial No. 454,828.

To all whom it may concern:

Be'it known that T, BURKE BRADBURY, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Signal-Receiving Systems, of which the following is a specification.

My present invention relates to signal re ceiving systems, and more particularly to signaling systems employing continuous radio frequency currents. The object of, my invention is to provide a simple and efficient means for producing an audible indication of signals transmitted by means of radio frequency continuous currents.

In carrying out my invention, I provide at a receiving station a source of audio frequency current which is associated with an electron discharge device and a detector in such a way that when no signaling currents are impressed upon the system there will be no appreciable flow of audio frequency current in the detector circuit. When, however, a radio frequency signaling current is impressed upon the system this signaling current is modulated by means of the audio frequency source and the modulated radio frequency signaling current is transmitted to the detector circuit where 'it is rectified and the rectified current is used to produce the desired audible indication.

The novel features which I believe to be characteristic of my invention are set forth with particularly in the appended claims. My invention itself, however, both as to its organization and method of operation will best be understood by reference to the following description taken in connection with the accompanying drawing in which I have illustrated diagrammaticall one way in which my invention may carried into effect.

As indicated in the drawing, my receiving apparatus comprises an electron discharge device 1 having an electron emitting cathode 2, an anode 3, a third electrode 4 in the form of a plate, and a discharge controlling member or grid 5 interposed between the cathode and other electrodes. By means of the battery 6, a constant positive potential is impressed upon the anode K and the third electrode 4 is connected to a point 7 in this battery so that a smaller positive potential 1s impressed upon the third electrode 4. The potentials of the battery 6 and the point 7 are preferably so chosen that a negative reslstance will be produced in the circuit between cathode andthird electrode 4. A source 'of audio frequency current 8 which 1s connected in the circuit between the oathode and discharge controlling member impresses upon that circuit at all times an audio frequency current. The circuit between cathode and third electrode contains an inductance 9 and a variable capacity 10 which are tuned to the frequency of the signals which it is desired to receive. An auxiliary circuit containing a detector 11 is coupled by means of the inductance 12 to inductance 9 and this circuit may also be tuned by means of a variable capacity 13 to the frequency of the signals to be received.

A resistance 14; is preferably included in the circuit between cathode and third electrode and this resistance is adjusted to a value slightly greater than the critical value at which the circuit becomes self-oscillating so that when no signaling currents are being received no current of signaling frequency will be produced in the circuit.

Vhen no signals are being received no appreciable amount of audio frequency current will be produced in the detector circuit and in the telephone receivers 15 because of the fact that the detector circuit and the circuit with which it is associated are both tuned to the radio frequency of the signal and the coup-ling between 9 and 12 is too loose to permit the transfer of any appreciable amount of audio frequency current. When signals are received upon the antenna 16 and impressed upon the circuit between cathode and discharge controlling grid by means of the coupling transformer 17, the potential of the grid 5 will vary at a radio frequency corresponding to the frequency of the signaling current, this radio frequency being modulated in accordance with the audio frequency source 8. A modulated current of radio signaling frequency will then be produced in the circuit 9, 10 and this moduated radio frequency current will be transferred to the detector circuit by means of the coupling 9, 12, and when rectified in that circuit-by the action of the detector 11, will produce an audio frequency current in the telephone receivers 15.

While I have shown and described the preferred embodiment of my invention, it will be apparent that my invention is, by no means limited to the particular circuit arrangement shown but that many variations in the connections employed as well as in the form of apparatus used may be made without departing from the scope of my in vention as set forth in the appended claims. What I claim as new and desire to secure by Letters Patent of the United States, is 1. The combination in a signal receiving system of an electron discharge device havingan electron emitting cathode, an anode, a third electrode and a discharge controlling member, electric circuits connecting said cathode with each of the other electrodes, sources of potential applied to said circuits in such away as to produce a negative resistance in the circuit between cathode and third electrode, means for impressing signaling currents of radio frequency upon the circuit between cathode and discharge controlling member, means for. continuously impressing audio frequency currents upon said circuit and a detector circuit loosely coupled to the circuit between cathode and third electrode, the circuit between cathode and third electrode and the detector circuit being resonant to the signaling frequency and the positive resistance of the circuit between cathode and third electrode being of a value greater than the critical value at which oscillations will be generated in the circuit. I

2. The combination in a signal receiving system of an electron discharge device having an electron emitting cathode, an anode, a third electrode and a discharge controlling member, electric circuits connecting said cathode with each of the other electrodes, sources of potential applied to said circuits in such a way as to produce a negative resistance in the circuit between cathode and third electrode, means for impressing signaling currents of radio frequency upon the circuit between cathode and discharge controlling member, means for continuously impressing audio frequency currents upon said circuit and a detector'circuit loosely coupled to the circuit between cathode and third electrode, the circuit between cathode and third electrode and the detector circuit being resonant to the signaling frequency.

3. The combination in a signal receiving system of an electron discharge device having an electron emitting cathode, an anode, a third electrode and a discharge controlling member, electric circuits connecting said cathode with each of the other electrodes, sources of potential applied to said circuits in such a way as to produce a negative resistance in the circuit between cathode and third electrode, means for impressing signaling currents of radio frequency upon the circuit between cathode and discharge controlling member, means for modulating the signaling current at an audio frequency, and a detector circuit loosely coupled to the circuit between cathode and third electrode, the circuit between cathode and third electrode and the detector circuit being resonant to the signaling frequency. I

4. The combination in a signal receiving system of an electron discharge device having an electron emitting cathode, an anode, a third electrode and a discharge controlling member, electric circuits connecting said cathode witheach of the other electrodes, sources of potential applied to said circuits insuch a way as to produce a negative resistance in the circuit between cathode and third electrode, means for impressing signaling currents of radio frequency upon the circuit between cathode and discharge controlling member, and a detector circuit loosely coupled to the circuit between cathode and third electrode, the circuit between cathode and third electrode being resonant to the signaling frequency.

5. The combination in a signal receiving system of an electron discharge device having an electron emitting cathode, an anode, a third electrode and a discharge controlling member, electric circuits, connecting said cathode with each of the other electrodes, sources of potential applied to said circuits in such a way as to produce a negative resistance in the circuit between cathode and third electrode, means for impressing signaling currents of radio frequency upon the circuit between cathode and discharge controlling member, means for modulating the signaling current at an audio frequency, and a detector circuit loosely coupled to the circuit between cathode and third electrode, the circuit between cathode and third elec trode being resonant to the signaling frequency.

6. The combination in a signal receiving system of an electron discharge device having an electron emitting cathode, an anode, a third electrode and a discharge controlling member, electric circuits connecting said cathode with each of the other electrodes, sources of potential applied to said circuits in such a way as to produce a negative resistance in the circuit between cathode and third electrode, means for impressing signaling currents of radio frequency upon the circuit between cathode and discharge controlling member. means for continuously inipressing audio frequency currents upon said circuit, and a detector circuit loosely coupled to the circuit between cathode and third electrode, the circuit between cathode and tlnrd electrode being resonant to the signalling irequency, and the resistance of the circuit between cathode and third electrode being of a value greater than the critical value at which oscillations will be generated in the circuit. 7

7. The combination in a signal receiving system of an electron discharge device having an electron emitting cathode, an anode, a third electrode and a discharge controlling member, electric circuits connecting said cathode with each of the other electrodes, sources of potential applied to said circuits in such a way asto produce a negative resistance in the circuit between cathode and third electrode, means for impressing signaling currents of radio frequency uponthe circuit between cathode and discharge controlling member, means for modulating the signaling current at an audio frequency, and a detector circuit loosely coupled to the circuit between cathode and third electrode, the circuit between cathode and third electrode and the detector circuit being resonant to the signaling frequency, and the resistance of the circuit between cathode and third electrode being of a value greater than the critical value at which oscillations will be generated in the circuit.

8. The combination in a signal receiving system of an electron discharge device having an electron emitting cathode, an anode, a third electrode and a discharge controlling member, electric circuits connecting said cathode with each of the other electrodes, sources of potential applied to said circuits in such a way as to produce a negative resistance in the circuit between cathode and third electrode, means for impressing I signaling currents of radio frequency upon the circuit between cathode and discharge controlling member, and means associated with the circuit between cathode and third electrode for producing an audible indication of the modulated high frequency current flowing therein, the circuit between cathode and third electrode being resonant to the signaling frequency.

, 9. The combination in a signal receiving system of an electron discharge device having an electron emitting cathode, an anode, a third electrode and a discharge controlling member, electric circuits connecting said cathode with each of the other electrodes, sources of potential applied to said circuits in such a way as to produce a negative resistance in the circuit between cathode and third electrode, means for impressing signaling currents of radio frequency upon the circuit between cathode and discharge controlling member, means for modulating the signaling current at an audio frequency, and means associated with the circuit between cathode and third electrode for producing an audible indication of the modulated high frequency current flowing therein, the circuit between cathode and third electrode being resonant to the signaling frequency.

In witness whereof, I have hereunto set my hand this 22nd day of March, 1921.

BURKE 'BRADBURY. 

